Friend,my Victory arrows are almost a mirror image of yours.The 3" thick slab of mini cell foam stops them in about 21".Eventually it will get cut up enough that some will pass through.I then replace the center as outlined above.
I forgot to say that when using it for quiver foam,I make holes in the foam as a start for my broadheads to keep them even.It is a simple matter to grind the starter holes with a Dremel.
The stuff has a million other uses.I haven't discovered them all yet but I'm working on it.